defmt-test: Exit with semihosting exit

[Urhengulas]

This PR makes probe-rs detect exit as successfully. Basically the same as knurling-rs/app-template#71.

[jonathanpallant]

LGTM. Can you post a log from a test run?

[Urhengulas]

@jonathanpallant Of course.

Successful run:

$ cargo test --test integration
    Finished test [optimized + debuginfo] target(s) in 0.07s
     Running tests/integration.rs (target/thumbv7em-none-eabihf/debug/deps/integration-1421b1a08557c90d)
     Erasing sectors ✔ [00:00:00] [######################################] 12.00 KiB/12.00 KiB @ 23.35 KiB/s (eta 0s )
 Programming pages   ✔ [00:00:00] [######################################] 12.00 KiB/12.00 KiB @ 26.45 KiB/s (eta 0s )    Finished in 0.993s
(1/4) running `it_works`...
(2/4) running `it_works2`...
(3/4) running `it_works3`...
(4/4) running `it_works4`...
all tests passed!

Panic:

$ cargo test --test integration
   Compiling krate v0.1.0 (/home/urhengulas/Documents/github.com/knurling-rs/krate)
    Finished test [optimized + debuginfo] target(s) in 0.17s
     Running tests/integration.rs (target/thumbv7em-none-eabihf/debug/deps/integration-1421b1a08557c90d)
     Erasing sectors ✔ [00:00:00] [######################################] 12.00 KiB/12.00 KiB @ 27.83 KiB/s (eta 0s )
 Programming pages   ✔ [00:00:00] [######################################] 12.00 KiB/12.00 KiB @ 30.35 KiB/s (eta 0s )    Finished in 0.852s
(1/4) running `it_works`...
(2/4) running `it_works2`...
(3/4) running `it_works3`...
ERROR panicked at 'assertion failed: false'
└─ integration::tests::it_works3 @ tests/integration.rs:24  
Frame 0: exp_u128 @ 0x00001b70
Frame 1: __udf @ 0x00000afe inline
       ./asm/lib.rs:48:1
Frame 2: __udf @ 0x0000000000000afe
       ./asm/lib.rs:51:17
Frame 3: udf @ 0x000002ee inline
       /home/urhengulas/.cargo/registry/src/index.crates.io-6f17d22bba15001f/cortex-m-0.7.7/src/asm.rs:43:5
Frame 4: panic @ 0x00000000000002ea
       /home/urhengulas/Documents/github.com/knurling-rs/krate/src/lib.rs:13:5
Frame 5: panic @ 0x000002c8 inline
       /home/urhengulas/.cargo/git/checkouts/defmt-7f5b74b4e6ff55d4/e36e12a/defmt/src/export/mod.rs:133:14
Frame 6: it_works3 @ 0x00000000000002c4 inline
       /home/urhengulas/Documents/github.com/knurling-rs/krate/tests/integration.rs:24:9
Frame 7: __defmt_test_entry @ 0x00000000000002a6
       /home/urhengulas/Documents/github.com/knurling-rs/krate/tests/integration.rs:8:1
Frame 8: fmt @ 0x0000013c
Frame 9: fmt @ 0x0000013c
Error: CPU halted unexpectedly.
error: test failed, to rerun pass `--test integration`

Caused by:
  process didn't exit successfully: `probe-rs run --chip nRF52840_xxAA /home/urhengulas/Documents/github.com/knurling-rs/krate/target/thumbv7em-none-eabihf/debug/deps/integration-1421b1a08557c90d` (exit status: 1)

I think the error case the stack trace should not be printed either, should it? probe-run does print the backtrace as well. And in case the test does not panic explicitly the backtrace is probably also quite useful.

[Urhengulas]

probe-run does print ERROR the program panicked instead of Error: CPU halted unexpectedly.. Which I think is better. But I feel this is a separate topic of "Make probe-rs detect panics".

[Urhengulas]

@jonathanpallant Can I merge?

[Urhengulas]

I have to say that the probe-run backtrace actually looks better.

probe-run:

ERROR panicked at src/lib.rs:25:5:
OMG!!!
└─ panic_probe::print_defmt::print @ /home/urhengulas/.cargo/git/checkouts/defmt-7f5b74b4e6ff55d4/e36e12a/firmware/panic-probe/src/lib.rs:104
────────────────────────────────────────────────────────────────────────────────
stack backtrace:
   0: HardFaultTrampoline
      <exception entry>
   1: lib::inline::__udf
        at ./asm/inline.rs:181:5
   2: __udf
        at ./asm/lib.rs:51:17
   3: cortex_m::asm::udf
        at /home/urhengulas/.cargo/registry/src/index.crates.io-6f17d22bba15001f/cortex-m-0.7.7/src/asm.rs:43:5
   4: panic_probe::hard_fault
        at /home/urhengulas/.cargo/git/checkouts/defmt-7f5b74b4e6ff55d4/e36e12a/firmware/panic-probe/src/lib.rs:86:5
   5: rust_begin_unwind
        at /home/urhengulas/.cargo/git/checkouts/defmt-7f5b74b4e6ff55d4/e36e12a/firmware/panic-probe/src/lib.rs:54:9
   6: core::panicking::panic_fmt
        at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/panicking.rs:67:14
   7: krate::abc
        at src/lib.rs:25:5
   8: main
        at tests/integration.rs:8:1
   9: Reset
(HOST) ERROR the program panicked

probe-rs

ERROR panicked at src/lib.rs:25:5:
OMG!!!
└─ panic_probe::print_defmt::print @ /home/urhengulas/.cargo/git/checkouts/defmt-7f5b74b4e6ff55d4/e36e12a/firmware/panic-probe/src/lib.rs:104 
Frame 0: exp_u128 @ 0x00001bfc
Frame 1: __udf @ 0x00000b8c inline
       ./asm/lib.rs:48:1
Frame 2: __udf @ 0x0000000000000b8c
       ./asm/lib.rs:51:17
Frame 3: udf @ 0x00000410 inline
       /home/urhengulas/.cargo/registry/src/index.crates.io-6f17d22bba15001f/cortex-m-0.7.7/src/asm.rs:43:5
Frame 4: hard_fault @ 0x000000000000040c
       /home/urhengulas/.cargo/git/checkouts/defmt-7f5b74b4e6ff55d4/e36e12a/firmware/panic-probe/src/lib.rs:86:5
Frame 5: panic @ 0x000003f6
       /home/urhengulas/.cargo/git/checkouts/defmt-7f5b74b4e6ff55d4/e36e12a/firmware/panic-probe/src/lib.rs:54:9
Frame 6: exp_u128 @ 0x00000d1a
       /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/num/bignum.rs:195:17
Frame 7: abc @ 0x00000372
       /home/urhengulas/Documents/github.com/knurling-rs/krate/src/lib.rs:25:5
Frame 8: __defmt_test_entry @ 0x000002ac
       /home/urhengulas/Documents/github.com/knurling-rs/krate/tests/integration.rs:8:1
Frame 9: fmt @ 0x0000013c
Frame 10: fmt @ 0x0000013c
Error: CPU halted unexpectedly.

[Urhengulas]

@jonathanpallant Can I merge?

I will just go ahead.